1. Field of the Invention
This invention relates to a watch including a display provided with an EL (electroluminescence) device, a solar battery, or the like and a light transmitting metallic dial.
2. Description of the Background Art
If a lamp, light emitting diode, EL device, and the like are built in and these are allowed to emit light for illuminating a symbol and hands for indicating time, the time can be determined even in a dark place. Hence, watches using an EL device, a light emitting diode, or the like in a display have lately been developed.
Conventionally, such a watch using an EL device is proposed in U.S. Pat. No. 4,775,964; Japanese Patent Application Laid-open Nos. 291192/1992 and 248088/1991, and the like.
Among these, displays of watches using an EL device proposed in U.S. Pat. No. 4,775,964 and Japanese Patent Application Laid-open No. 291192/1992 are now explained.
FIG. 27 is a sectional view of a display described in U.S. Pat. No. 4,775,964.
In the display of a watch using an EL device shown in this figure, a symbol 121 called "time characters" indicating time and the like is directly formed by printing or the like on the surface of an EL device 130 mounted on a movement 110 of the watch.
However, in such a display, the symbol 121 is directly formed on the surface of the EL device 130 and hence the appearance as a display is impaired, thereby decreasing the product value.
Also, the color of the display is limited to the color (generally a cream color) of the EL device 130 itself so that there is no coloring freedom.
Japanese Patent Application Laid-open No. 291192/1992 proposes a display which solves such a problem.
FIG. 28 is a sectional view of the display disclosed in Japanese Patent Application Laid-open No. 291192/1992.
The display shown in FIG. 28 comprises a metal layer 131 and a transparent display 120 sequentially laminated on an EL device 130. A symbol 121 indicating time is formed on a transparent plate 120.
Here, the metal layer 131 is formed by coating a metal such as gold, silver, or the like on the EL device 130. The transparent display 120 is directly mounted on the EL device 130 via the metal layer 131.
For the display having such a structure, the appearance and coloring freedom can be improved compared with the display shown in FIG. 27, since the transparent display 120 indicating time and the like is mounted on the EL device 130.
However, in a display such as shown in FIG. 28, the light from the EL device 130 is blocked by the metal layer 131 and hence there is a problem that the display is dark.
Also, the color of the display shown in FIG. 28 is limited to the colors of the EL device 130 and the metal layer 131 when the EL device 130 emits light, and to the color of the metal layer 131 when the EL device 130 does not emit light, whereby the coloring freedom is insufficient.
Further, in such a structure as shown in FIG. 28, because the transparent display 120 and the EL device 130 are intimately combined via the metal layer 131, light interference fringes such as a Newton's ring or the like appear, exhibiting the problem that the appearance, collecting efficiency, and the like are more impaired.
Other than the above, as watches using an EL device and an emitting diode, those having a structure in which a light diffracting plate and a display are secured to the surface of a movement together with an EL device and lamp or emitting diode are proposed. The dial securing structure disclosed in Japanese Utility Model Publication No. 84886/1993 show an example of such a structure.
In the securing structure disclosed in Japanese Utility Model Publication No. 84886/1993, a transparent display and a diffraction plate, which is disposed facing the back face of the transparent display and has almost the same shape as the transparent display, are secured to a casing frame using a double faced adhesive tape.
Such a display fixing structure has the advantage that the light diffraction plate and the transparent display can be simply secured to the casing frame using a double faced adhesive tape. On the contrary, in the display fixing structure, the transparent display cannot be aligned with the casing frame and hence the alignment is entrusted to a working method such as measurement by eye, resulting in unstable alignment.
Also, because the transparent display and the casing frame are attached together using a double faced adhesive tape, separation of the transparent display from the casing frame is difficult so that there is the problem that fabrication repairs and after-sale services are difficult.
On the other hand, reflecting recent environmental problems, new merits of a clean solar battery have been discovered and hence watches using such a solar battery are being developed.
Examples of the securing structure of a watch in which a solar battery is secured to the surface of a movement together with a display include various structures in which a solar battery is exposed, making use of the color of the solar battery itself; time characters and the like are directly printed on the surface of a solar battery; a transparent seal provided with time characters and printing for decoration is attached to a solar battery and this solar battery is secured using a fixed member; and the like.
Other than the above structures, structures have been proposed in which a decorative parting plate is assembled at the periphery of a solar battery and a pin for the parting plate is pressed into a watch movement, while a solar battery is supported with the parting plate, to secure the solar battery; a light transmitting display is incorporated into the surface side of a solar battery when a watch casing is mounted to support the light transmitting display with the watch casing and thereby to secure the solar battery; and the like.
Conventional structures for securing a solar battery and a display are now explained with reference to the drawings.
FIG. 29 is a sectional view schematically showing a watch in which a transparent seal is attached to the surface of a solar battery.
In the solar battery securing structure shown in this FIG. 29, a transparent seal 151 provided with decoration by printing or the like is attached to the surface of a solar battery 140 excepting the portion for a hand shaft 152 and a solar battery securing member 153 is combined with a movement 110, thereby securing, to a movement 110, the solar battery 140, to which the transparent seal 151 is attached.
FIG. 30 is a view showing a watch equipped with a solar battery in which the solar battery is secured using a parting plate. FIGS. 30(a) and 30(b)are a schematically sectional view and its top plan view respectively.
The watch equipped with a solar battery as shown in FIG. 30 has a structure in which a securing pin 154a for a parting plate 154 provided with printing and the like is engaged in a plurality of holes 110a provided in a flange portion of a movement 110, thereby incorporating the parting plate 154 into the movement 110 and sandwiching the solar battery 140 between the parting plate 154 and the movement 110 to secure the solar battery 140 to the movement 110.
FIG. 31 is a schematically sectional view showing the case of supporting a solar battery mounting a light transmitting display by a watch casing.
In the solar battery securing structure shown in FIG. 31, a casing 155 is installed on a movement 110 which is completed by incorporating a solar battery and a solar battery securing member 153 for aligning the solar battery 140, and a light transmitting display 160 is incorporated at the same time as the armor 155 is installed to secure the light transmittable display 160 by the casing 155 in the condition where the watch is completed.
However, there are the following various problems in these conventional solar battery securing structures.
First, in the structure shown FIG. 29, since the transparent seal is directly attached to the surface of the solar battery, replacing only the attached transparent seal is difficult when failure of the transparent seal is observed after the manufacture of the watch has been completed. In this case, the expensive solar battery must also be replaced at the same time.
Also, for the watches in which the seal is attached in this way, product variations are limited after the movement is completed and reapplication of the adhesive seal is difficult. Further, there are the problems that the working characteristics are impaired and the productivity is low.
The use of the solar battery securing structure shown in FIG. 29 has led to increased costs for the watch as a whole.
On the other hand, in the securing structure shown in FIG. 30, the surface of a solar battery is exposed. Since the color tone of the solar battery is determined in advance, the product is not too attractive even if the design of the parting plate is altered. Specifically, there is the problem that the design is greatly limited.
Also, the securing structure shown in FIG. 31 has the drawback that the position of the light transmitting display mounted on the solar battery is not determined while the casing is installed after the hands are attached, which is a cause of instability, exhibiting the problems of extremely impaired working and handling characteristics.
Further, because the transparent display 160 is arranged directly on the solar battery 140 in the same manner as in the display shown in FIG. 28 light interference fringes such as a Newton's ring or the like appear in the display using a solar battery shown in FIG. 31, exhibiting the problem that the appearance, collecting efficiency, and the like are impaired.
As is clear from the above explanations, conventional watches using an EL device, solar battery, or the like, have the various drawbacks that the color of the display is limited to that of the EL device or the solar battery whereby there is little coloring freedom and the appearance is impaired, fabrication, dismounting, and the like are not easy, and if a transparent display is arranged to improve the appearance and the like, light interference fringes such as a Newton's ring or the like appear at the boundary between the transparent display and the EL device or the solar battery due to light refraction, whereby the appearance, collecting efficiency, and the like are impaired.